1. Field
The present disclosure relates to devices that remove pollutants from roadway surfaces. More specifically, the embodiments described herein include pollutant traps, such as porous filters, pads, or membranes, that attach to the under carriage of moving vehicles and collect roadway pollutants that are liberated from the road surface. Methods of using these devices to remove pollutants from the environment are also provided.
2. General Background
According to the Environmental Protection Agency (EPA), nonpoint source pollution (NPS) is now the leading cause of water quality problems in America. NPS is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into coastal waters, lakes, rivers, wetlands and even our underground sources of drinking water. (See, for example, “Oil in the Sea” in Pollution Equipment News, dated October 2002.) These pollutants are many and varied, but they include oil, grease and toxic chemicals from urban runoff and energy production. Atmospheric deposition and hydromodification are also prime sources of NPS.
The accumulation of hydrocarbons and toxic metals on roadway surfaces is largely attributable to tailpipe emissions, tire tread wear, leaking automotive fluids, brake pad deterioration, and dirty car-washing water. (See U.S. Pat. No. 5,993,372, the entirety of which is hereby expressly incorporated by reference.) As tailpipe exhaust is emitted, for example, the many “fine” particles in the exhaust are either inhaled or they are filtered back down back down on to the street, waiting for rain to wash them into a storm sewer or for rolling tires to throw them back into the air (also referred to as “re-entrainment.”) Fine particles, carbon monoxide, nitrogen oxides, volatile organic compounds, toxic organic compounds (e.g., toluene), and other heavy metals are all found in tail pipe exhaust. Additionally, as tire tread wears, pollution accumulates on roadway surfaces in the form of zinc, cadmium, carbon black, and fine particles of rubber. Furthermore, leaking oil, antifreeze, brake and transmission fluids, battery acid, grease and degreasing agents, also accumulate on the roadway surfaces. These automotive liquids contain toxic organic compounds and metals, as well. Brake pad dust is also a major source of roadway pollution and significantly contributes to the accumulation of copper in our waterways. In the San Francisco Bay, for example, brake pad dust is reported to be the largest source of copper pollution. (See “How Do Vehicles Pollute the Bay? Let's Count the Ways” available at the Palo Alto (Calif.) Regional Water Quality Control Plant web site.)
The accumulation of roadway pollution is having a drastic effect on human health. In a study financed largely by the National Institute of Environmental Health Sciences, researchers calculated that the number of deaths from lung cancer increases by eight percent for every ten micrograms of fine particulate matter per cubic meter. The risk of dying from lung cancer as well as heart disease in the most polluted cities has been compared to the risk associated with nonsmokers being exposed to second-hand (cigarette) smoke over a long period of time. (See Jeanie Davis, “Air Pollution Increases Lung Cancer Risk; Evidence Links Bad Air with Heart Disease, Too” MSN and WebMD Medical News, Mar. 5, 2002.”) Since the number of automobiles is increasing three times faster than the rate of population growth in the world and approximately 40% of deaths around the world can be attributed to various environmental factors, especially organic and chemical pollutants, the need for a device and method to remove these toxins from roadway surfaces is manifest. (See BioScience, October 1998 issue.)
Several different devices have been made to trap pollutants that are emitted from automobiles (e.g., U.S. Pat. Nos. 6,170,586, 5,711,402, 5,993,372, 5,967,200, 5,549,178, 5,692,547, and 6,524,992, all of which are hereby expressly incorporated by reference in their entireties). Although these devices and approaches reduce pollution by trapping the pollutants before they contact the roadway surfaces, there remains a significant need for devices and methods that remove pollutants that have already accumulated on roadway surfaces.